I bought a 2004 A6 S-line the other day only and found out it has an oil leak. With all the info on this site it sounds like its the valve cover gaskets, but I've also read its due to the PCV clogging and building pressure in the crank case. If this is the case then I would want to replace my PCV, correct? And I haven't found any threads on diagnosis or even replacement of the PCV.

When replacing the gaskets, how do I get to the PCV and see if that is the culprit?

 

Congrats on the purchase!

most probably its not pcv. with the 2.7 and 2.8 you most probably have a leak in the valve covers, cam adjuster seals, cam plugs. there are many DIY articles for these leaks online if you want to replace them yourself. mechanic will probably take $800.

keep an eye on the oil level.

if you have a serious leak you might also want to check out the oil pan.

 

Welcome to the club nick L. You now have your 1st posting under your belt. There are several common oil leak locations. Here's a couple of links to get you started.
Audi Parts - Vw Parts - Audi Parts Vw Parts Kit Company - Blauparts
http://www.audiworld.com/tech/eng.html

VC gaskets are pretty straight forward, but the cam chain tensioner gaskets have some tricks to them. Also, readup on what tools are needed. For the tensioners, you will need special tensioner tool which is ~$10-15 online. I had an oily mess too with the 2000 A6 my son bought. Had leaks at VC, cam tensioners, cam seals, oil pan, & front main seal. Good luck on the new buy.

 

the breahter ("PCV") system is pretty straight forward to check. check the hoses for integrity. then just pop them off and see what's in there. it is common to find some oil in the hose, what you are looking for is "gunk" buildup. then just check the pancake valve to make sure that isn't gummed up (again, straightforward). if the breather is clogged, the buildup in pressure can "push" oil past the valve cover gaskets. either way you will probably want to replace those.

good luck